The present invention relates to a lifting mechanism for the pressing roller of the feed mechanism of a crusher for scrap. The rotor of the crusher, via a lifting mechanism that acts upon a mounting bracket of the rotor mounting, can be removed from a split housing after an upper part of the housing has been raised about a horizontal pivot axis and has been secured in position relative to a lower part of the housing. Pivot arms are disposed on opposite faces of the housing and are connected to hydraulic cylinders, with free ends of the pivot arms being pivotably mounted about a horizontal pivot axis that extends parallel to the pivot axis between the upper and lower parts of the housing. The pivot arms, via appropriate pins, are successively connected to the upper part of the housing to raise the same, with the mounting bracket after the upper part of the housing is secured relative to the lower part of the housing in an open position and the pivot arms have again been lowered, and, after the rotor has been removed, again with the upper part of the housing.
With such crushers for scrap, it is necessary to have lifting mechanisms for maintenance operations on the housing and the rotor, and lifting mechanisms for the pressing rollers disposed in the feed mechanism.
A lifting mechanism is known for maintenance operations on a crusher that has a two-part raisable machine housing, the plane of separation of which between the lower and upper parts of the housing extends through the center of the rotor axis.
A respective pivot arm is mounted on both sides of the upper part of the housing, and is actuated by a hydraulic cylinder.
The pivot arms are provided with securing and coupling means, with the use of which it is possible to successively raise the upper part of the housing, to remove the rotor together with its mounting from the lower part of the housing, and to subsequently secure the rotor in the raised position to the raised upper part of the housing (U.S. Pat. No. 4,718,614, which belongs to the assignee of the present application).
Also known is a pressing roller/lifting mechanism, where two pressing rollers are successively arranged in a support frame, the swivel joint of which is disposed on that side remote from the crusher (German Offenlegungsschrift 33 01 186). The purpose of the pressing rollers is to precompress the scrap that is to be crushed, and to control the supply of the scrap. To fulfill these functions, the pressing rollers are driven, and their height is adjustable. To adjust the height of the pressing rollers, a support frame is provided that is pivotably mounted on the feed mechanism, and is customarily actuated by double-acting hydraulic cylinders.
A drawback of such heretofore known crushers is that a large number of hydraulic components, such as hydraulic cylinders and control valves, are necessary for actuating the pressing roller/lifting mechanism and for the lifting mechanism for maintenance operations; the hydraulic components of the lifting mechanism for maintenance operations, although they are connected for only a very short period of time, are subjected to a great standstill wear due to the vibrations and shocks that constantly occur during operation of the crusher.
It is an object of the present invention to improve a lifting mechanism of the aforementioned general type in such a way that the total number of lifting mechanisms required for the operation of a crusher having a feed mechanism is reduced, while at the same time the operational reliability of the remaining hydraulic components is increased.